Você não precisa definir os URLs de repo em ks.cfg, aqui está um exemplo de kickstart que eu uso atualmente com rhel6.
# interactive install from CD-ROM/DVD
interactive
install
cdrom
key --skip
lang en_US.UTF-8
# keyboard us
#
clearpart --all --initlabel
part /boot --fstype ext4 --size=100
part pv.100000 --size=1 --grow
volgroup vg00 --pesize=32768 pv.100000
logvol / --fstype ext4 --name=lvroot --vgname=vg00 --size=15360
logvol swap --fstype swap --name=lvswap --vgname=vg00 --size=2048
logvol /var --fstype ext4 --name=lvvar --vgname=vg00 --size 5120
timezone Europe/Paris
firewall --disabled
authconfig --useshadow --passalgo=sha512
selinux --enforcing
#skipx
# pre-set list of packages/groups to install
%packages
@core
@server-policy
acpid
device-mapper-multipath
dmidecode
# ... and so on the list of packages/groups I pre-customize (and with - those I don't want)
vsftpd
wget
xfsprogs
-autoconf
-automake
-bc
# ... and so on
#-----------------------------------------------------------------------------
# postinstall, execution avec chroot dans le systeme installé.
%post --interpreter=/bin/sh --log=/root/post_install.log
echo -e "================================================================="
echo -e " Starting kickStart post install script "
# do some extra stuff here , like mounting cd-rom copying add-ons specific for my product